This article is a short, informal history of the ribosome field that begins with the emergence of the field in the 1930s and ends with a description of its state in 2007, the year this essay was written. The growth in our understanding of both the role of the ribosome in protein synthesis and its structure is emphasized. Starting in 2000, the field experienced a massive upheaval as a result of the publication of the first atomic-resolution crystal structures for ribosomes. However, by 2007, the field had recovered sufficiently so that one could begin to understand how it was likely to evolve in its "poststructural" era. For that reason, this essay is about as useful as a short history of the ribosome field today as it was several years ago, when it was written.

This chapter summarizes the current knowledge about Bacillus ribosomes and translation factors. Much of the information concerning Bacillus ribosome structure and function has been obtained from work with Bacillus stearothermophilus, while most of the genetic analysis has been carried out with B. subtilis. Available information about ribosome structure and genetics in other gram-positive systems are also summarized in this chapter. B. subtilis contains 10 rRNA operons.The sequences of the rrnB and rrnO operons have been determined; they show an organizational pattern identical to that of the E. coli rRNA operons, containing genes for 16S, 23S, and 5S rRNA in that order. Ribosomal-protein gene characterization was initiated by the isolation and mapping of mutations conferring resistance to antibiotics that were known to target the translational machinery. A number of mutants that have alterations in components of the translational apparatus and exhibit defects in sporulation have been identified. These include mutants with altered sensitivity to antibiotics that act on the ribosome and temperature-sensitive mutants that result in spore-minus or spore-conditional phenotypes. In E. coli, sequences in the promoter regions of genes sensitive to the stringent response have been identified, and it has been proposed that (p)ppGpp acts directly as an effector in modulating promoter recognition by RNA polymerase. Expression of a fusion of the B. subtilisrrnO promoter to lacZ was repressed by induction of the stringent response by the addition of serine hydroxamate in wild-type strains but not in a relA-minus mutant.